On formation of scar tissue / by Charles S. Sherrington and Charles A. Ballance.

[From the Journal of Phijdoloyy. Vol X. No. 6, 1889.]

ON FORMATION OF SCAR-TISSUE. By CHARLES S.
SHERRINGTON, M.A., M.B., &c., Fellow of Gonville and
Gains College, Cambridge, and CHARLES A. BALLANCE,
M.B., M.S., Lond., F.R.C.S., Erasmus Wilson Lecturer in Pathology
in the Royal College of Surgeons of England, etc. (Plates XXXI.,
XXXIL, XXXIIL)\

{From the Physiological Laboratory of St Thomas's Hospital, London.)

In the course of a research by one of us (B.) into the process of
occlusion of arteries after ligation, it seemed desirable to form an
independent opinion of the part played by the elements of the arterial
wall in the production of the fibrous tissue which eventually closes
the vascular channel. The following experiments were carried out in
the hope of their furnishing, to ourselves at least, some answer to the
disputed question of the origin of inflammatory tissue. Are the color-
less corpuscles of the blood, capable as we know them to be of passing
from the vessels into the intervascular tissue, also the source of the
new tissue which the inflammatory process may produce ?

Cohnheim's reply to this question was an affirmative, at least as
positive as are the discoveries brilliant which it was based upon. For
Cohnheim the colorless corpuscles which wandered from the blood
vessels in an area of inflammation were not only the source of pus
cells when pus appeared, but were the formative cells for the new
tissue if any new tissue were formed. From this position in the
question he never withdrew. In the edition of the Vorlesungen only
two years prior to his untimely death again with renewed insistance
he supported it. It was from his laboratory that most of the obser-
vations emanated which bring evidence in favour of this " leucocytic "
view. They are set forth in papers from the Institute at Breslau
by Senftleben'^ and by B. Heidenhain^; and by Senftleben*

1 The preparations with the drawings were shown in March of this year at the Royal
College of Surgeons in illustration of part of the Erasmus Wilson Lectures on "Ligation
in Continuity."

2 Virchoiv's Archiv, Vol. lxxii.

Ueber d. Verfettimg fremder Koiyer in d. Bauchhdhle, 1872.
Vircliow's Archiv, Vol. lxxvii.

ON FORMATION OF SCAR-TISSUE.

551

and by Tillmans^ from the Institute at Leipsic. Among observers
who independently of contact with Cohnheim published opinions in
harmony with his upon this question, may be named especially
Schede^, Aufrecht^ Bizzozero^ and Zieglerl

Upon the evidence furnished by the researches of Ziegler Cohn-
heim laid a quite exceptional stress. The conclusions of the then
Assistant in the Wurzburg laboratory have had much to do with the
ascendancy of Cohnheim's teaching on the point. They have been
incorporated by Ziegler himself in the well-known Lehrbuch der Fatho-
logische Anatomie.

Ziegler placed little oblong chambers, made by fastening at the
four corners two cover-glasses a slight distance apart, under the skin
of the dog, and left them for a certain length of time. The cleft
between the glasses became filled with cells, which could be examined
directly under a microscope. He found these cells to be leucocytes,
many of which were fatty, and resembled the ordinary cells of pus.
But in many experiments after a time actual formation of tissue took
place in the layer of cells between the glasses. Cells were found in all
stages from the lymphoid to the epithelioid and giant-cell type. Certain
cells seemed to grow large at the expense of their neighbours whose
protoplasm was appropriated by the larger growing cell. He judged
that his preparations proved that the giant cells of granulation tissue
are at least in some cases produced from the wandering colorless
corpuscles of the blood, and further that the giant cells produce both
blood vessels and connective tissue. " So war dadurch der Nachweis
geleistet " " dass bei der Entziindung die ausgewanderten Zellen eine
gewebsbildende Rolle spielen."

Ziegler's researches were taken as furnishing experimental proof
that not only do migrated white blood cells in certain numbers become
pus corpuscles, but that they also in certain numbers are capable
of further development, and are the primary source of cicatricial
tissue.

Ziegler's conclusions were in fact similar to those of Cohnheim.
A considerable number of writers have controverted them. Baum-

1 Virchoio's Archiv, Vol. lxxviii.

^ Arch. f. klin. Chir., xv.

3 Virchoiv's Archiv, Vol. xmv.

^ Annali universi di Medicina, 1868.

5 Exper. Unters. iib. d. Herkunft d. Tuherkelelemente, 1875, and Unters. ub. path.
Bindegeicehs u. Gefdssneubildung, 1876.

552 C. S. SHERRINGTON AND C. A. BALLANCE.

garteii\ Bottcher", Ewetzky^, Weiss^ Hamilton^, all have at
various times raised a voice against it, denying to the migrated blood
cells any power of further development. According to them the forma-
tion of scar-tissue is in no way directly due to elements existing in the
blood ; the fibrous tissue does not arise from leucocytes. Quite notably
have those histologists who have studied the process of occlusion of
blood vessels assumed a sceptic attitude amid the general acquiescence
in the Cohnheim-Ziegler doctrine. We will point out the writings of
Thiersch', Riedel', Auerbach', Pick', Heuking and Thoma'"
and most recently and very definitely Hunter^^; as we follow the
opinions of these observers chronologically toward the present time
more and more pronounced do we find the tendency to deny to leu-
cocytes an exclusive share in the replacing of coagulum, &c. by cica-
tricial tissue.

From the foregoing it is evident that a very desirable side light,
might be thrown on the question upon which one of us (B.) was
engaged, by an examination elsewhere than in a ligated blood vessel,
of this capability of leucocytes to produce a fibrous connective tissue.
It was determined to repeat the classical experiments of Ziegler. We
may remark that we began work with an educational bias favourable
toCohuheim's view.

Methods employed.

Two circular cover-glasses, each | of an in. in diameter and '006 of
an in. in thickness, were fastened together so as to form a little flat
glass chamber, in the manner employed by Ziegler. A strip of tin-
foil placed between them at their edge along \^ of their circumference
was cemented by shellac on each face to the corresponding surface
of the cover-glass. The tiny chamber thus formed had therefore

1 Die sogenannt. Organis. des Thrombus, Leipzig, 1877.

2 Ziegler' s Beitrdge zur pathologischen Anat. ii. 2.

3 Unters. aus der path. Instit. zu Zurich, iii.

* Archivf. klinische Chirurgie, Bd. xxiii, 1879.

^ Spongegrafting. Edin. Med. Journ., 1881.

6 Pitha u. Billroth. Bd. i. Abth. 2, § 549.

' Zeitschr. f. Chirurg., Bd. vi. 1876.

8 Ueber die Obliteration der Arterien nach Ligatur, 1877

» Zeitschr. f. Heilkundc, Bd. vi. 1886.

Virchow's Archiv, Vol. cix. 1887.
" Gold Medal Thesis for M.D. Edin. unpublished.

ON FORMATION OF SCAR-TISSUE.

553

between the two ends of the strip of tin-foil an opening into the
interior. The tin-foil first employed was -J^ mm. thick ; that thickness
was inconvenient, as the depth of the chamber was then too great for
higher powers of the microscope to explore. Tin-foil 2V thickness
was subsequently employed. With this thickness membranes were
obtained between the cover-glasses that made very satisfactory micro-
scopical specimens. Fig. 18, Plate XXXIII.

These chambers for eight and forty hours before use were emptied
of air and filled with distille'd water previously sterilized, or with
nutrient broth containing peptone according to the recipe of Koch.
Both the chamber and the fluid in which it was kept were again
sterilized by heat an hour or so before being used for experiment. In a
few instances the air was not entirely expelled.

The animals employed by us have been in all cases rabbits or
guinea-pigs. During every experiment the animal has been deeply
under the influence of an anaesthetic. Antiseptic precautions were
vigorously maintained throughout all the operations. No suppuration
ever occurred. Had it done so in any experiment we should have
excluded the results of that experiment. In our earlier experiments
the chambers were placed in the peritoneal cavity ; in the later into the
subcutaneous connective tissue of the flank.

The chambers were allowed to remain within the animals for various
periods, from four hours at shortest to 18 days at longest. When the
chamber was removed its contents were examined either fresh upon
a warm stage under the microscope, or after appropriate treatment
with hardening and staining reagents. The outsides of the chambers
were often covered with, thin films of young fibrous tissue — these
films were examined by the same methods as were the contents.
The reagent chiefly employed was osmic acid, either in freshly made
•57o watery solution, or in vapour from a l7o solution. In the former
case the chamber taken warm from the body was at once plunged into
the osmic acid solution or was rapidly split open, and with the contents
so exposed, placed in osmic acid. In the solution of osmic acid they
remained for an hour, in the dark. Where osmium vapours were used
the same plan was adopted, except that the chamber was always opened
unless bubbles of air happened to have got ingress previously, as some-
times happened. Exposure to the vapour was ensured by placing the
specimen between two watch-glasses, at the bottom of which was osmic
acid solution, or by suspending from the cork of a bottle containing the
solution. The action of the osmic acid was allowed about two hours'

554 C. S. SHERRINGTON AND C. A. BALLANCE.

play, always in the dark. The preparations with osmic acid were,
after washing in water, mounted either in Farrant's gum solution, or
after dehydration, in xylol-balsam. They were in some instances after-
stained, with picrocarmine, with fuchsin, methylene blue, eosin, or most
frequently with haematoxylin (Ehrlich's solution). Other preparations
were made without the use of osmic acid. In these after hardening
in chromic acid, or in alcohol, or Fleming's solution, picrocarmine,
methylene blue, eosin, fuchsin, haematoxylin, etc. were used.

For the observations on living specimens a warm stage of Strieker's
pattern was used.

Contents of the Chambers.

One of the first steps which we took was to examine the serous
moisture of the abdominal cavity of the rabbit and guinea-pig, and of sub-
cutaneous wounds and the blood in order to ascertain the characters of
the cellular elements contained therein. The examination was conducted
by the cover-glass method first recommended by Koch and Loffler.
Eosin, fuchsin, saffranin and methylene blue were used as stains.
Some preparations were made by exposing the moist film on the
cover-glass to vapours of osmic acid solution.

The examination revealed the presence in the serous moisture and
in the tissue plasma of at least two kinds of cells. The one kind re-
sembled in all respects the leucocyte, the colorless cell of the blood.
This kind was in fact indistinguishable from the leucocyte.

A second kind of cell was also present and sufficiently numerous.
This cell, which is much larger in size than is the former kind, when
fixed by osmic acid vapour, often presents a discoid figure, some 30yu,
to 40yLt across ; not infrequently however, and more frequently than not
when fixed by plunging into osmic acid solution, or by drying, as in the
Koch-Loffler method, the cell outline is irregular, often angular, with
especial prominence of one angle or of two ; in the last case the cell
might be described as fusiform. Whatever the shape of the body of the
cell may be, there always lies within it, generally towards the centre, a
laro^e oval vesicular nucleus, itself somewhat laro^er than the red cor-
puscle of the blood. It does not stain so darkly as does the nucleus of
a leucocyte. The substance of the flattened plate-like cell-body is
markedly granular, particularly so when prepared by the rapidly drying
method. The protoplasm reduced to a flattened flake as it generally is,
may be of such tenuity near the margin that in the fresh condition and

ON FORMATION OF SCAR-TISSUE.

555

in many osmic acid preparations the outline of the cell is somewhat
difficult to distinguish. The determination of the limits of the cell is
however rendered easier by the fact that the cell substance is very
granular, the granules taking a sepia tint with osmic acid, and being
readily stained by fuchsin and other aniline colours. A marked charac-
teristic of these cells is their tendency to occur in masses and clumps. In
the masses the outlines of the individuals are often hard to recognise.
In specimens examined fresh upon the warm stage the granules are
many of them brilliant and highly refracting, though not to such an
extent as are fatty particles. Granules of various size exist in one and
the same cell.

Four Hours. — The shortest sojourn we allowed the chambers was
four hours in the subcutaneous tissue. The chambers were found to
contain fluid with a few blood corpuscles, not collected into rouleaux, and
unaltered in appearance. No fibrin had appeared. In short, mixed
with the bouillon was simply a trace of blood, as yet unclotted.

Within the chamber in the neighbourhood of its opening were
however a large number of leucocytes, unmixed with red blood
corpuscles or indeed with any other kind of cell. None of these
wandering cells had apparently penetrated far into the recess of the
chamber, because there appeared an obvious gap between the position
of their pioneers and the diluted blood elements occupying the chamber
elsewhere.

Nine and a Half Hours. — Nine and a half hours after insertion
into the abdominal cavity, the diluted blood was also found unclotted —
although in this instance the chamber had been filled not with bouillon
but with water sterilized. The trace of blood which almost unavoidably
found its Avay into the chambers at the time of their insertion had
remained unclotted in all specimens examined earlier than fifteen hours.
The bouillon containing peptone, seemed, as indeed one might have
expected, to retard the clotting of the blood that entered the chamber.
In chambers filled with nutrient peptone-bouillon no clot was ever
found earlier than twenty hours after the original implantation. On
the other hand we found a very considerable formation of fibrin in a
chamber that had been filled with sterilized water and then allowed a
sojourn of eighteen hours in the subcutaneous tissue. The nutrient
bouillon contained commercial peptones, and we think the peptones
may not so rapidly diffuse but that this retardation of the clotting
may be explained by their presence.

In the early specimens of fibrin production in the tissue plasma

556

a S. SHERRINGTON AND C. A. BALLANCE.

which filled the chambers we had abundant examples of the formation
of fibrin filaments as fine straight or very slightly curved lines, irregu-
larly radiating from granular nodal masses. The nodal granular debris,
under various reagents, appeared to consist, as the generally accepted
view affirms, of altered blood-platelets, and leucocytes undergoing
alteration.

About the nodal points of the network of fibrin the leucocytes were
grouped. Both on the warm stage and after fixation by osmic acid
these leucocytes displayed only rarely any deviation from the spheroid
form. There were indeed some instances in which they presented a
fusiform outline, or possessed a tiny process jutting from the cell body.
Such examples were extremely sparse, and occurred only in the neigh-
bourhood of the opening of the chamber, and in certain situations to be
specified immediately. For the most part the cells seemed in an inert
condition, as far as one can judge of their activity from their form. In
the short time between ex.traction of the chamber from the body and
the fixation in osmic acid or the observation of the cell upon a warm
stage under the microscope, their vitality had suffered sufficiently for
the cell to have assumed its zero of shape, the subspheroid figure. Or
for some reason existence within the Ziegler's chamber was not con-
ducive to activity of the protoplasm, yet from what we shall relate there
is no good reason for thinking that the leucocytes within the chamber
are in a very different state from those invading the inflamed tissue
without. The latter supposition is favoured by the fact that the larger
cells, plasma-cells as we shall term them, also found in the chambers
under similar circumstances, although subjected to the same technique
of preparation as these leucocytes, showed well-marked amoeboid move-
ments.

Indeed if the latter of the two suppositions just suggested be not
accepted, it becomes necessary to assume that of these two kinds of cell
the leucocyte is much the more perishable and delicate, and was
practically annihilated by a simple procedure that did not appear to
interfere with the vitality of its co-occupant the plasma-cell.

Here must be mentioned another sign of degeneration in the
leucocytes examined in these chambers \ Many of them showed the
triple and multiple nuclear bodies that are universally regarded as
evidence of the lethal disintegration of the nucleus — as Fleming names
it, the fragmentation " of the nucleus. On the other hand the cell-

^ Kuss, Palis, ISiG. Paget, Surgical Pathol, p. 151.

ON FORMATION OF SCAR-TISSUE. 557

body of the leucocyte was not granular or fatty, but fairly evenly
though deeply tinted by the osmium. These points are seen in Fig. 1,
Plate XXXI.

Eighteen Hours. — In chambers removed after the appearance of
fibrin within them, but before the stay within the body had exceeded
eight and forty hours, it was usual to find a number of areas in which
leucocytes were present in much greater numbers than elsewhere.
Fig. 2, PL XXXI.

The tendency to collect to certain points which the leucocytes
evinced in even very early specimens was more marked in these later
preparations. About the nodal points of the fibrinous network crowds
of them were present. The outlying individuals were frequently
arranged in lines along the converging filaments of fibrin. The older
within certain limits these films of coagulum the more obvious the
aggregation of the leucocytes into certain groups. For convenience on
account of their prominence and apparent importance in subsequent
stages we have been accustomed to refer to these groups shortly as the
cell-islets. Cf. Fig. 3, PI. XXXI. They are little collections of cells,
occurring constantly, scattered about in the thin cellular membranes
which grow over and within the glass chambers. Some are obvious to
the naked eye, especially when the film has been treated with carmine
or with haematoxylin, which show them as deeply colored points. They
vary in size from a small pin's head downward. The larger islets are
often compounded of smaller ones. The smallest display best what we
believe to be the structure originally characteristic of all : — a centre
of amorphous albuminous debris surrounded by leucocytes; less fre-
quently one or two altered red blood corpuscles form the centre.

It was in specimens of this date that the first evidence of the
presence of another cellular element than the leucocytes and red cells of
the blood was found. Cells similar to the large flattened plate-like
forms of the peritoneal moisture, already adverted to, began to be found
in the chamber. The time of their advent varied within narrow limits
when the chamber rested in the subcutaneous tissue ; when in the
peritoneal cavity there was much greater variation in respect to time.
This we believe was due to the chamber not coming to rest in one
particular spot for some time after introduction into the abdomen.
The movements of the viscera seemed able to shift it and prevent its
forming adhesions. When put into the abdomen we always placed
it about an inch to right or left of the little wound in the linea
alba through which it was inserted. But we never found it anywhere

558 a S. SHERRINGTON AND G. A. BALLANGE.

near that situation after a sojourn of more than a few hours. In the
course of four and twenty hours the chamber had nearly always passed
toward or actually into the position which it almost constantly came
permanently to take, that is, a little distance from the median line
in front of the psoas muscle at the very root of the mesentery. Once
there it appeared in a few hours to contract adhesions, and become
fixed in a permanent fashion. Until bound down by adhesions, the
full complement of cells did not reach the interior of the chamber.

In one instance, in a chamber exposed for eighteen hours in the
subcutaneous tissue, plasma-cells were found in considerable numbers
near the opening. They were indistinguishable in appearance from
the plasma-cells of the normal subcutaneous tissue, except that a
greater variety of individual form was to be seen in them. In later
specimens the plasma-cells were found scattered throughout the whole
chamber, although most numerous near the opening.

Seventy-two Hours. — In a preparation from a chamber which
had been seventy-two hours in the subcutaneous tissue, plasma-cells
entered into the formation of the islets even in the portions furthest
removed from the opening. At the opening however no other kind
of cell was mixed with them, which was not the case elsewhere. No
forms intermediate between the leucocyte and the plasma-cell were
to be found ; they were repeatedly expected and repeatedly looked for,
but the search was unsuccessful.

The preparations gave an almost bewildering number of examples
of the infinite variation in shape of the large amoeboid plasma- cells,
which also varied very considerably in size, and as to granules. The
body of the cell was for the most part plate-like, being in many
instances extended into so thin a film that its exact limit was hard
to determine, especially when, as occasionally happened, the granules
of the cell-body were less pronounced towards the periphery. Some
idea of the wide diversity of outline exhibited by individual cells may
be gathered from our figures. Of. Figs. 1, 4, 5, 6, 7 and 8, Plates XXXI.
and XXXII.

It must not be thought, however, that in any of its forms the
plasma-cell could not be distinguished with certainty from the leuco-
cyte. In the same way as in the peritoneal moisture and in the
plasma of subcutaneous tissue, the forjuer is here also on the warm
stage and in osmic preparations, characterised by larger size, coarser
granules, the constant presence of a single clear nucleus of oval figure,
and by the differences in staining qualities and mobility already

ON FORMATION OF SCAR-TISSUE.

559

referred to. We may here add that these differential characters may
be obscured by faulty methods of examination.

In the specimens obtained from chambers that had rested for
seventy-two hours in the subcutaneous tissue of the guinea-pig,
we found individuals among the plasma-cells, which showed well-
marked vacuolation. Figs. 1, 4, 5, PI. XXXL For the most part the
matter within the vacuole was a granular debris that furnished no
sufficient clue as to its nature. But in a few it was indisputable
that the vacuole contained, more or less altered but still perfectly
easily recognisable, a leucocyte or red blood corpuscle. In Fig. 4 is
shown the appearance presented by one of these cells. A large
vacuole contains a somewhat faintly stained body, which is finely
granular and indistinctly nucleated. It is a little smaller than is
the nucleus of the plasma-cell itself. Fine threads seemed to pass
from the sides of the vacuole across the cavity to the substance of the
included leucocyte. Taken with the context afforded by examination
of other cells in the neighbourhood we believe that this and other
similar instances were examples of leucocytes lying in vacuoles in the
plasma-cells. Many stages of ingestion could be found. Cf. Figs. 1,
4, 5, PI. XXXL Simple approximation, the hollowing out of a little
bay in the side of the plasma-cell into which the leucocyte was as it
were drawn, partial inclusion, total inclusion — all these were exem-
plified. And further there were many vacuoles in which mere granular
debris lay. This debris was, we think, probably the still undigested
remnant of the ingested leucocyte or red blood cell. We doubt whether
without very special apparatus the cells of the tissues of mammalia
can be kept in sufficiently normal condition for sufficient length of
time to compass observations on ingestion by living cells ; we were
however much assisted in the interpretation of the appearances of the
osmic fixed preparations by the processes described by Miss M. Green-
wood for the Rhizopoda. Her observations^ were conducted on living
specimens of Amoeba proteus and Actinosphaerium, and she was able to
follow in these animals under the microscope all the visible phenomena
accompanying the ingestion of prey. In our preparations we had as it
were a number of amoebae, many of which had been actively engaged
in ingesting living prey, immediately before the reagent had been used
that killed them so rapidly as to allow no time for any great departure
from their previous aspect.

1 This Journal, Vol. vii. p. 253, Vol. viii. p. 263.

5G0 C. S. SHERRIXGTOX AXD C. A. BALLAKCE.

Nor were leucocytes the only bodies to be found within the
substance of the plasma-cell. Red corpuscles of blood were recog-
nisable in them. Very frequently along the border of the space in the
chamber, the plasma-cells lying in great numbers near the cement (shellac
glue) which fixed the strip of tin-foil to the glass, were filled with tiny
droplets of oil that became deep black under the treatment with osmic
acid. Sometimes the entire cell was dotted, except just round the
nucleus, with fine fatty particles of a fairly equal size : sometimes the
oil was collected into a few much larger globules. The cement itself
turned deep black under osmic acid treatment. There was little room
for doubt that the black particles in the plasma-cells were derived from
the cement near the cells ; whether the cells took up the particles
without altering them, or whether the particles were in any degree a
food for the cells are points we can give no answer to.

Contiguous plasma-cells or even those a little distance apart were
often connected together by their processes (Figs. 1, 5, 7 and 8,
Plates XXXI. and XXXII.). The bands of connection might be short
thick arms or long gossamer threads of protoplasm. By similar arms
and threads the cells seemed to adhere to the most diverse objects in
their surrounding. The surface of the cover-glass, a filament of fibrin,
a hair, a fibre of cotton, a lump of the cement fastening the sides of the
chamber together, all afforded points to which the processes from the
plasma-cells would cling (Figs. 14 and 15).

There were present also in chambers of eighteen hours', twenty-
two hours', twenty-six hours', forty-eight hours', and seventy-two hours'
standing, as also in others of older date containing well formed granu-
lation tissue, many giant cells (Fig. 6) — huge multi-nucleate cells, that
obviously in many instances were cell-fusions. Congregations of large
plasma-cells as before mentioned were frequently met with. They
adhered one to another in groups. And here many collections of them
existed intermediate in character between those groups in which the
individual cells were agminated but easily distinguishable from one
another, and giant cell masses in which the nuclei were the only
guides to the individual position of the coherent members. Some
appeared to be cell-fusions ; many did not. In these latter the nuclei
were gathered together into an iiTegular heap. The ring-like arrange-
ment of the nuclei frequently found in the giant cells of tubercle was
never observed in these membranes by us.

Of nuclei in these giant cells there existed apparently two kinds.
One was large, clear, and oval, having all the characters of the nucleus

ON FORMATION OF SCAR-TISSUE.

561

of the separate plasma-cell ; it was invariably present in all the giant
cells. The other sort was smaller, round, more darkly tinted by osmium
treatment, and was not invariably present, that is, did not exist in every
giant cell, but was in some cells even more numerous than the larger
oval variety. We doubt very much the accuracy of describing the
latter smaller bodies as true nuclei. We incline to believe, from
their great similarity to some of the leucocytes observed in the plasma-
cells, that they are nothing but leucocytes surrounded by the substance
of the giant cell and somewhat altered in appearance. Against this
supposition is the fact that there was often no indication of a vacuole-
space around the ingested cell, but in support of it the substance of
the plasma-cell was seen sometimes very closely applied to the ingested
leucocyte in instances in which there was very little doubt as to the
nature of the included body. In osmic preparations there is generally
a light space free from granules immediately around the oval nucleus
of the plasma-cell that simulates somewhat closely the appearance of
a vacuole about the nucleus itself

Advancing further into the chamber, in the specimens of more than
forty-eight hours' duration, the plasma-cells begin to apply themselves
to the islet-groups of leucocytes. Cf Figs. 8 and 10. They surround
the leucocytes. The islets come to consist of a central portion made
up of leucocytes, and an outer zone of large and granular plasma-cells.
In this way the islets seem to increase rapidly in size. Neighbouring
islets appear to become merged together. Giant cells are frequent in
them, especially, it would appear, near, although not actually at, the
centre. Most of the growth that went on in the membrane appeared
to consist in enlarfjement of individual islets, and the fusion of neioh-
bouring islets. The islets appeared to be the chief growing points of
the tissue. But it is true that gradually a more or less continuous
sheet of plasma-cells is formed over the intervening space between the
islets. When very thin the inflammatory membrane consisted of a
layer of scattered cells lying separated by considerable but fairly regular
distances one from another. Each individual cell was of a discoid or
fusiform figure, and granular, with a large clear nucleus. The edge
of the disc was thin and often deeply scalloped ; it merged, under all
methods of staining used by us, at certain points quite imperceptibly,
in a tenuous film which composed the bulk of the membrane proper.
When fixed with osmic acid and after-stained with haematoxylin
(Ehrlich's), this membrane is shown to contain, if not to be entirely
made up of, a feltwork of filaments, like filaments of fibrin. These
PH. X. 39

562 a S. SHERRINGTON AND G. A. BALLANGE.

cross in every direction in the plane of the membrane, without
prominent arrangement in any one particular sense. The individual
filaments vary a good deal in size. Fig. 16, PL XXXIII.

It was among the plasma-cells of the fringe of the islets that we
noticed the earliest regularly fusiform cells, the immediate precursors of
fibrous elements in the new tissue. It is true that plasma-cells of an
irregular spindle-shape were observable not rarely among even the
earliest of the plasma-cell swarm entering the chamber. But in those
instances the outline was probably but one of- many which the amoeboid
cell successively assumed, and generally it was not of the same character
as the regularly fusiform type prevailing among these plasma-cells in
the outskirts of an islet. In that latter the majority of the cells lay
in lines concentrically set about a core of ill-stained, broken-down matter
that composed the centre of the mass. Cf Fig. 11, PL XXXII. The
fusiform fibroblasts began in fact the encapsulation of the debris of the
breaking-down blood cells, &c. The lengthening out and assuming of
a regular spindle form took place also very early in those cells that
had become attached to hairs and cotton-fibres, and lumps of the
shellac glue. They were soon found adhering there in rows of regular
disposition, the rows consisting entirely of typical young fusiform
fibroblasts.

Later than seventy-ttuo hours.

Older specimens revealed further progress in the formation of a
fibrous-tissue membrane. After a stay of eight days, or ten days, or
fourteen days in the subcutaneous tissue in many instances the islets
consisted of plasma-cells alone. The leucocytes had disappeared. Tlie
pigmented remnants of the red blood corpuscles were much longer
traceable. In many places along certain lines the spindle-shaped cells
had become attenuated, and formed distinct bands and often long and
delicate cords (Figs. 12, 13). In many places in the tenth day
specimens, and in some of the eighth day ones an inter-cellular substance
showing fibrillation exists (Fig. 12). This extra-cellular matter is well
seen where, as occasionally happens, a single chain of fusiform fibro-
blasts, set in end-wise series, has produced a thread-like tiny cord.
Each fibroblast appears to lie in a sheath of fibrillated matter. The
delicate lines marking the fibrillae run parallel to the contour of the
celL The fibrillated matter was not tinted by osmic acid or by any of
the stains employed by us to the same depth as the granular substance

ON FORMATION OF SCAR-TISSUE.

563

of the cell itself. The granules of the cell-body, the clear oval nucleus,
were still marked characters of the plasma-cell, although it might be
considered at this stage to have become a fixed corpuscle of connective
tissue.

We were unable to satisfy ourselves on the question as to whether
the fibrillated extra-cellular matter had been formed by direct trans-
formation from the surface portion of the cell-body, or whether it
had arisen as a secretion from the protoplasm of the cell. But the
latter view appears to us the most probable, if only for the reason that
the fibroblast-cell and its new capsule of fibrillated matter are when
taken together much larger than, so far as we have observed, the
individual naked fibroblast ever is.

From the islets the bands of spindle cells spread away in various
directions. The determination of the direction of the earliest-formed
chains of spindle cells seemed to us greatly due to the lines taken by the
filaments of the original fibrin-network ; the radiation from the same
nodal points, the interlacing not always at acute angles but frequently
in rectangular fashion.

In membranes of ten, fourteen, and even eighteen days' growth, not
all the cells nor even the majority were spindle-shaped. A vast
number were triradiate, and multiradiate ; some had but one process ;
very few were rounded. Many recalled to mind the branched fixed
corpuscles of the cornea. Long tapering branches united cell to cell,
not only the cells of one plane one with another, but the cells of
different planes also (Figs. 8, 9 and 17). A meshwork of infinite
variety and complexity was thus established. But in all these examples
of plasma cells in the stable as well as in the previously described labile
forms, the granular nature of the cell substance and the clear oval
nucleus were characters never lost.

In the same manner as did the more delicate strands of fibrous
tissue, larger, broader sheets and beams arose. In all the spindle cells
side to side as well as end to end are separated by intervening matter
fibrillated in a direction parallel to the longer axes of the cells.

It may have been noticed that no mention has been made of any
developing blood vessels in the membranes examined. It is a striking
fact that in none of the preparations, not even in the preparations of
eighteen days' growth, taken from the peritoneal cavity, did we find in
any instance any trace of a formation of blood vessels. Nowhere were
capillaries to be found ; although the chambers were bound by adhesions
and in the later specimens encapsuled in cicatricial tissue. This obser-

39—2

564 C. S. SHERRINGTON AND C. A. BALLANCE.

vation seems to furnish a negative to the view advanced by Creighton
that the giant cells of granulation-tissue are exclusively vaso-factive.
Here we had giant cells in abundance, but never any capillary forma-
tion. Perhaps the film of tissue in the chamber was thin enough
to allow sufficient nutriment to reach the cells by fluid soakage only.

Abstract of some of the Notes of the Experiments.

The number of hours mentioned corresponds to the time during
which the chambers rested in the bodies of the animals.

1. 4 hours. Subcutaneous. No fibrin. No rouleaux of red cells. A

large number of leucocytes in the neighbourhood of the mouth of
the chamber.

2. 18 hours. Subcutaneous.

High power. Fibrin network very extensive. Crowds of leucocytes
at the nodal points of fibrin. Cells circular in outline, nuclei
crescentic or trilobed. At the periphery of the islet a few leuco-
cytes still in an active state and of irregular form. At the mouth
of the chamber are a few large plasma and giant cells. Fig. 2,
PI. XXXI.

Low power. The islets of cells in the fibrin film are well seen. Indeed
they are visible to the naked eye, about the size of pins' heads.

3. 72 hours. Subcutaneous.

Islets more marked. Fibrin network very extensive. Numerous large
plasma-cells encircling the islets of leucocytes at the nodal points.
In the neighbourhood of the mouth of the chamber the plasma
corpuscles are more numerous, and the islets are partly made up of
these cells. Moreover, numerous red and white blood cells are visible
in the vacuoles of giant cells and in those of separate plasma-
cells.

72 hours. Peritoneal cavity.
The chamber was quite free. No trace of an adhesion.
The chamber seems to have escaped the leucocytic immigration. The
islets are formed almost entirely of plasma-cells.

4. 8 days. Peritoneal cavity. Fixed by an adhesion ; how long fixed %
The islets are formed of plasma-cells alone. The leucocytes have all

disappeared, a few only are visible in the vacuoles of the larger
cells. The cells at the circumference of the islets are lengthened
out along the lines of fibrin, and joined with others free of the islets
to form a giant cell field, or plasmodium. Every cell is connected

ON FORMATION OF SCAB-TISSUE.

565

by long ])rocesses with others, so that looked at in one way the
whole field is one giant cell. The islets consist often of one giant
cell together with numerous plasma corpuscles. It is only at the
periphery of the islets that the contour of the individual plasma-
cells can be made out. See Fig. 8. Foreign bodies such as blood-
clot, shellac, etc. are surrounded by a capsule of spindle cells.
Fig. 11.

5. Several chambers. 8 to 18 days in peritoneal cavity. Some fixed,
and some not fixed by adhesions.
Fibrillation advanced. Every stage can be observed, from the simple
fusiform elongation of the plasma-cell to the development of a
})erfect fibril. Fig. 12.

The above experiments seemed to point to a certain definite period
at which the migration of leucocytes and connective tissue corpuscles
occurred.

In order to examine somewhat further the behaviour of the
leucocytes and of the plasma-cells respectively toward the chamber,
a slight modification of the mode of experiment was used on two
occasions. Two chambers (or four) were placed side by side in the
subcutaneous tissue. At the end of twenty-two hours they were taken
out, one was dropped into osmic acid, and the other was sealed with
warm paraffin. The sealing was done by dipping the mouth of the
chamber into a soft paraffin melting at 107*^ Fahrenheit. Only the
part of the chamber immediately next the opening was touched by the
paraffin, which was just above the temperature of solidification. After
being sealed the chamber was placed in the abdominal cavity of a
second guinea-pig, there to remain for incubation.

In this way it was possible to compare the contents of two cham-
bers which had been placed side by side in the subcutaneous tissue,
and whose contents were presumably the same at the time of with-
drawal. One was then fixed for histological examination. The other
incubated for a longer period, no new cells being allowed to enter during
this second incubation.

The imperviousness of the chambers after sealing was tested iu the
following two ways :

(a) A little IVq hydrochloric acid was introduced in the chamber,
the outer edge of the opening carefully dried, and then the paraffin
applied by dipping the mouth just as in the experiment above. The
chamber was then placed in blue litmus. No change took place in the
litmus, although the chamber remained a week in the solution.

56G

G. S. SHERRINGTON AND G. A. BALLANGE.

(/3) A little of an active culture of Spirillum Finkleri was intro-
duced into the chamber, the edge of the opening cleaned, and then
sealing performed as before. The chamber was then placed in nutrient
broth (in another case in nutrient gelatine) for a week, at a temperature
of 35° C. No growth appeared in the broth (or gelatine). In a control
tube the broth was turbid in two days.

In the experiments performed in this way the appearances observed
in the chambers were alike. The chambers were withdrawn at the end
of tweuty-two hours, one was then incubated further for another forty-
four hours.

The contents at end of twenty-two hours were as follows, viz. : —
a large number of leucocytes and several patches of red corpuscles.
Plasma-cells are also present but very sparsely; they are most numerous
at the mouth of the chamber. They are scattered at long intervals.
In one place a few plasma-cells are collected around some red cells, and
a fibre of wool. Fibrin filaments are present in the chambers taken
from the rabbit, but none in those from the guinea-pig.

Contents of sealed chambers after forty-four hours' further incuba-
tion :

Fibrin network extensive. The leucocytes lie around the red cell
masses. The leucocytes possess for the most part fragmented " nuclei.
The plasma-cells are far more numerous. They exist in patches and
groups quite apart in many cases from the clots or the leucocytes.
Many plasma-cells lie mingled with the leucocytes around the little
blood-clots.

Remarks.

We have pointed out that there appears to be a definite sequence of
events in the processes induced within the tissue by implantation there
of the experimental chamber — processes which must according to
ordinary terminology be designated as inflammatory in nature. At a
definite time and in a definite order occur the immigrations respectively
of leucocytes and of the daughter cells of the tissue corpuscles. The
former had commenced at the end of four hours. In our experiments
the fibrin within the chamber was crowded with leucocytes within
eighteen hours of the time of insertion in the subcutaneous tissue of
rabbit or guinea-pig. But in those eighteen hours scarcely a plasma-
cell could be found to have penetrated into the chamber. On the other
hand after the lapse of seventy-two hours the nodal points, which had
been previously the centres of aggregation of leucocytes, had been

ON FORMATION OF 8CAR-TI8SUE.

567

tninsfonned into islets consisting chiefly of plasma-cells. This primary
leucocytic invasion and the subsequent appearance of " larger cells with
clear vesicular nuclei" has also been noted by Ziegler and by others.
W. Hunter^ passed by transfusion all the blood of one rabbit into the
peritoneal cavity of a second. At the end of a few hours he was able
to find scarcely a white corpuscle in the circulating blood; the amoeboid
cells had migrated into the peritoneal cavity where the foreign body —
tlie fluid blood or the coagulum — was resting.

This observed order in the occurrence of events serves to explain
"the periods of repose" that are known to the surgeon. The fluid
which oozes from the surface of a wound is at first blood tinged, but
soon becomes pale, until at the end of a few hours the surface is covered
with a whitish film. This film is a fibrinous network, containing within
its meshes leucocytes in enormous numbers, and ever increasing as
the first few hours pass by subsequent to the development of the film.
" Such a calm continues from one day to eight, ten, or more, according
to the nature and extent of the wounded part, and the general condition
of the body." " The calm may be the brooding time for either good or
evil ; whilst it lasts the mode of union of the wound will in many cases
be determined." " Moreover in open wounds the time at which on each
tissue granulations are produced is determined by this calm ; for they
begin to be distinctly formed at its end^" The share which we think
the white corpuscles have in the constructive process of repair will be
evident from what we mention elsewhere in the paper. " Apparently
they do not hinder it^" And previous to the advent of aseptic surgery
it was believed by many that to leave the cut-surfaces of a wound
exposed until they bore a whitish, glassy film, and not to put them
into contact until then, was to give a condition favorable to union by
primary adhesion.

Indeed, whatever view be adopted regarding the fibroblastic value of
the leucocyte, certain other purposes which it may subserve in the
process of repair were in our experiments extremely obvious. It was
the pioneer of all the wandering swarm of cells that visited the intruding
occupant of the tissue. Whatever causes, intrinsic or extraneous,
guided its early voyaging, the route it traversed and the position it

^ Jouni. Anat. and Phys., Vol. xxi., 1887. "In 6 hours scarcely a white corpuscle
was to be found in a field of several hundred squares (instead of 4, 5, or 6 in every
100 squares) though the red cells were much increased in number."

- Paget, Surgical Pathology, Ed. iv. p. 151.

^ Ibid. Paget. . . . .

568 C. S. SHERRINGTON xiND C. A. BALLANCE.

assumed seemed to determine almost absolutely the course of after-
coming plasma-cells that appeared in great measure to be simply
followers along the track thus broken for them. Where the intruding
body was of penetrable nature, as in the case of blood-coagulum, these
leucocytes entered it in the van of a destroying army, that in turn
attacked it from channels that leucocytes had prepared. By leucocytes
the mass to be absorbed was in part previously divided up and made to
otfer a greater surface for absorption by plasma-cells. Wheie larger
masses of clot are concerned cracks and fissures occur from chemical
causes, as shown by one of us elsewhere (B.)\ which in the same way
allow of the entrance of the plasma-cells among whose functions in the
clot mass are absorption and substitution. The filaments of fibrin when
they were present appeared to direct to a certain extent the path
travelled by the cells. Certainly to group themselves about the
granular nodal points of the fibrinous network was quite characteristic
of the distribution of the leucocytic swarm, and this directly influenced
the formation of islets in the cellular membrane, the islanding being
the direct outcome of the original grouping.

And leucocytes served also as a pabulum for the active plasma-cells^.
Just as, in the extremely interesting observations given by M. Green-
wood^, little monads, Euglenae and Algae coexisting in the same water
with Amoeba proteus were by it ingested, so leucocytes become the
prey of the plasma-cell, and are by it included and ingested. And if
the growth and proliferation of the plasma-cells be of importance in the

1 Erasmus Wilson Lectures of the present year.

2 The plasma-cells are considered by Metschuikoff to be among his group of
"phagocytes." He writes : "Die weissen Blutkorperchen bilden einen allerdings ansehnli-
clien Theil aus der Summe der Phagocyten, indessen gehoreu zu diesen, wie ich in meinen
sammtlichen Arbeiten ausdriicklich erwahnt habe, auch amoboide Bindegewebs-zellen und
manche andere zellige Elemente." Virchow's Archiv, Vol. cvii. p. 239, 1887. He proposes
to call "grosse in der Kegel mit einem einfachen (uicht gelappten) Kerne versehene
Phagocyten," in which "der Kern ist rund oder haufiger oval," by the name Makrophagen,
no matter what their origin may be. This in contradistinction to the Mikrophagen, " mit
stark tingirbaren, zum grossen Theil gelappten oder fragmentirten Kernen und sehr
blassem Protoplasma," which are for the most part, he affirms, leucocytes. The plasma-
cells are therefore included in his Makrophagen. Cf. also Wyssokowitscli, Koch's
Zeitschrift, Bd. i. Lief. 1, p. 39, 1886. Metschnikoff studied the phagocytic power of
plasma-cells in subcutaneous tissue in cases of Erysipelas in the human subject. In some
preparations we have obtained lately in the Z iegler chambers from an experiment in which
the wound was allowed to suppurate, there are abundant instances of bacteria within the
plasma-cells. Cf. also Hess, Virch. Arch. Bd. cxix. Hft. 3, on "Gland cells destroying
bacilli."

3 This Journal, Vol. vii. p. 253. Vol. viii. p. 263.

ON FORMATION OF SCAR-TISSUE.

569

process of repair, what circumstance more propitious than the presence
in abundance of nutriment so delicately adapted and so highly organized
as the substance of the leucocytic cell ? Of Amoeba and Actino-
sphaerium it was remarked that the food most suitable to these forms
is unshielded non-coagulated proteid matter. A low degree of vitality,
a diminished activity of its protoplasm, renders an organism easier prey,
more readily captured and more readily absorbed. The plasma-cell
may in some respects be taken as a hothouse variety of amoeba ; it
finds its unshielded non-coagulated proteid in the dead or dying
leucocyte. It will be remembered that within the chambers the leu-
cocytes revealed striking signs of lowered vitality.

Not that the number of instances in which we could detect an
actually included or a partially ingested leucocyte would, we think,
account for the large disappearance of them that does actually occur.
Is it not probable that the plasma-cell can exert digestive action upon
material which it does not incept ? Suppose a proteolytic ferment
secreted by the plasma-cell, and leucocytes that are dead or dying as
in the above experiments ; a gradual solution of their substance in the
tissue plasma will occur, yielding to it an abundance of rich food
for other cells that are in a thriving condition.

Passing in review the chief points observed in regard to plasma- cells,
it became clear enough to us that in the study of their origin and
development lies the best key to the problems of the formation of
tissue of repair. We found them traceable up from forms of an
amoeboid kind, different in many ways from the amoeboid cell-forms of
blood and lymph, through individual types of almost endless diversity
of figure with the utmost variety of combination and interdependence,
onward finally to the fixed corpuscle of fusiform or of stellate shape
imbedded in fibrillated material.

As to giant cells, often it was obvious that the large cell had resulted
from a fusion more or less complete of the bodies of several smaller
cells, the nuclei of which remained distributed regularly through the
substance of the aggregate. In other instances a massing of the nuclei
of the giant cell about one point appeared to denote a mode of origin
from a single cell that had grown and undergone nuclear multiplication
without actual separance of the daughter cells from the parent as they
had been produced.

Again, by the union of cell with cell, by means of long pseudopodium-
like processes, it was sometimes found that a whole field under the lens
was occupied by the net-like ramifications of one huge multi-nucleated

570 C. 8. SHERRINGTON AND 0. A. BALLANCE.

C(j11 — better described perhaps as an unbroken slieet of anastomosing
cells. The characters of the giant cells in the implanted Ziegler-
chambers resembled in this particular those of such giant cells as occur
in marrow, growing bone, the splenic pulp, myeloid sarconia, and in
granulation tissue. In no cases did the arrangement of the nuclei in
them bear resemblance to the ring-like or other regular disposition
often seen in the giant cells of tubercle.

Upon the position of the giant cells depends partially the arrange-
ment of the fibrillated tissue which is ultimately produced. The run of
the bundles of fibrillae is often from and between giant cells. The cells
range themselves previous to fibrillation in lines spreading for some
distance from the giant cells; in fact in many ways the resemblance of
giant cells to cell-islets is a close one. Just as in some cases, if not
in all, the so-called giant cell is really but a congeries of smaller
coherent cells, attracted to one and the same spot for the purpose of
participation in a common prey, so is it with the cell-islets also. The
groups of leucocytes from which the cell-islets arise appear to be origin-
ally formed under the common attraction which is offered to these cells
by the albuminous debris present at the central nodes of the fibrinous
network. Later, the leucocytes themselves becoming from some cause
or another effete and of low vitality, exert a similar attraction upon
the wandering plasma-cells, and afford to them a rich and easy quarry.
By this arrival of fresh cells the islet is increased in bulk. The more
centrally situated individuals feed upon the leucocytes they have sur-
rounded, and the latter rapidly merge to an amorphous kernel for the
entire mass.

The outlying cells become disposed along definite lines, and as it
were sketch in in its main outlines the general plan which the adult
arrangement of the new fibrous tissue will display.

The cell-islets are the centres of most active growth and proliferation
in the young cellular tissue. They contain the stores of nutriment
that are gradually dissolved and digested. They may contain also
innutrient matters, and matters such as are not only innutrient but
incapable of solution by the cells or plasma. At first the shape of those
cells which are immediately next to the kernel of nutritious matter in
the islet is irregular, and suggests amoeboid properties in the cell ; later
the cell becomes almost regularly fusiform, and is applied by its side to
the material which gradually disappears. The material comes to be
encircled by chains of fusiform cells set concentrically around it. It
becomes encapsuled in the same way as is the ligature placed around an

ON FORMATION OF SGAIi-TISSUE.

571

artery by tlic surgO(jn, or as is any foreign body placed within a wound
which heals around it. The fusiform fibroblasts slowly exert the same
solvent action upon the imprisoned material as did their amoeboid
ancestors. No doubt the more easily affected portions of the material
are the first to go into solution and disappear, leaving a constantly
less amenable residue and a less nutrient one ; and perhaps it is in
accordance with the decreasing supply of food from this source that the
cells in contact with it undergo gradual change and lose their pristine
elasticity of form. They assume the spindle-shape, and a fibrillated
intercellular cement substance comes into existence between them.
We have already seen reason to think that this " matrix " is a secretion
from the cell. Prominent among the conditions under which the young
fibroblasts begin to form it is, it would seem, a diminution in the
amount of pabulum at hand to support growth. Much as amoeba under
adverse conditions assumes an encysted form, so where food is scanty
do the inherited tendencies of the fibroblast lead it into states of
quietude and encystment. The less nutritious, the more inert the
foreign body which the plasma-cells surround, the sooner do they
become fixed cells, the earlier do they elongate, and make around
themselves the bed of fibrillated matter, which commits them to im-
mutability of form. In the same specimen in which plasma-cells
preying upon remnants of blood-clot were still actively amoeboid, it
often happened that around innutritions matter as hairs, and cotton
fibres, the cells were already perfectly developed into young fibrous
tissue.

When embedded in the fibrillated secreted substance all digestive
and absorptive activities within the cell do not cease. Encapsulation
does not arrest absorption. This has been shown by one of us (B.)'.
It holds even in those instances in which the foreiijn substance is of
such a nature as to resist digestion or chemical solution for a lengthened
period. Carbolized cat-gut is quickly split up and destroyed by an
environment of living tissue ; kangaroo tendon, which is denser and
more resistent, becomes encapsuled and continues to be gradually
dissolved and absorbed after a dense fibrous investment has been
produced around it ; it may require a hundred days for complete
disappearance. Prepared silk in like manner becomes encapsuled, but
is finally absorbed in a period which sometimes is as lengthy as three
years. Even silve)- is slowly destroyed. Gold and platinum appear able
to resist indefinitely long.

^ Erasmus Wilson Lectures of the present year.

572 a. S. ^SHERRINGTON AND C. A. BALLANCE.

Uu fortunately it was only until the present experiments had been
concluded and the present paper very nearly so that we were able to
obtain copies of Professor Ziegler's monographs from the Wurzburg
Institute. We had been obliged to satisfy ourselves with the results of
his work in abstracts of the original papers. As a matter of fact our
work has not been a repetition of his quite to the extent we had
imagined. A great part of our observations deal with periods which his
do not touch or only slightly so. ^His first communication is based
upon observations on chambers implanted in sixteen dogs at thirty-six
different intervals. But of these only five, upon four individual
animals, refer to the first two weeks after implantation, and he records
no observations prior to the seventh day. Of our observations with
rabbits the major part refer to the first two weeks after implantation,
and our earliest observations were made only four hours after implan-
tation. We imagine too, judging from the beautiful illustrations to the
original papers, that the cell- masses that w^e have so frequently referred
to as cell-islets are included by him among the giant cells. It must
be remembered also, that his experiments date prior to the acceptance
of antiseptic surgery, and eleven times he records pus, either in the
implanted chambers or in the wound. In no case did we ever find the
slightest trace of pus, as we have said already.

It will have been seen that in most points our observations entirely
confirm the original observations made by Ziegler. One particular
there is however, and that one of fundamental importance, in which
we are in disaccord with the descriptions furnished in his paper. As
far as we observed, there are in the tissue-plasma of a part subjected
to irritation such as that described in the experiments tw«) kinds of cell.
On the one hand there are present leucocytes indistinguishable from
and probably identical with the colorless corpuscles of the blood; on
the other hand are plasma corpuscles, cell-elements proper to the
connective tissue of the part offended. The cell that plays as we
incline to believe the only actively constructive role in all the energetic
upbuilding of new tissue that goes forward in the part, is the plasma-
cell, a corpuscle absolutely distinct from the colorless corpuscle of the
blood. Our cover-glass preparations lead us to believe that these
free cells in small number exist in the tissue plasma even under
normal circumstances. Where the connective tissue corpuscles are
proliferating, as for instance within an inflamed area, there these free

1 Ziegler's second communication deals entirely with "die Schicksale der einge-
wanderten, zum Theil bereits veranderten Zellen von dem 25. bis 70. Tago."

OiV FORMATION OF SCAB-TISSUE.

573

tissue-cells are enormously more numerous. In our experiments, out of
them arose the permanent membranes, to be designated inflammatory
if the ordinary unsatisfactory use of the term be sufficient, which spread
themselves over and inside Ziegler's chambers when lying in a sub-
cutaneous space or in the peritoneal sac — membranes composed at first
of cells entirely similar to the corpuscles of the normal tissue-plasma.
Colorless blood-cells doubtless wandered in the surrounding of the
chamber, and doubtless entered in plenty the space within it. But
these leucocytes had no permanence of possession. The fibroblast of
the new tissue was not of leucocytic origin. Our observations yield no
support to Cohnheim's view of the genesis of cicatricial tissue from
leucocytes.

When pus is formed in an inflamed focus many of the migrated
colorless corpuscles of the blood become, as is well known, pus-cor-
puscles. It does not appear strange that where pus is not produced
those of the swarm of leucocytes, which do not drain off by lymphatic
channels from the tissue they have temporarily invaded but remain
behind, should not thrive within it. Many circumstances might, we
conceive, render their sojourn perilous. The high carbonic acid tension,
the comparatively stagnant character of the fluid, the presence of, to
them, unwonted chemical bodies, and of others in unwonted percentages
— these are instances of conditions which might, we conceive, constitute
an environment of disadvantage. And that the migrated leucocytes
should rapidly be not merely acclimatized in the new locality, but
should actually become fixed elements of the part, and generate the cells
of a fibrous tissue is to our minds improbable. The cells of fibrous
tissue and the colorless corpuscles of the blood are both of mesoblastic
origin, but we have no evidence that they are more nearly related one
to another than are the fibres of a striated muscle to the endothelial
cells of an artery. No one advances the view that of these latter one
can by any means be made to reproduce the other. Even in tumours
with their apparent departure from the normal type of growth the
principle of heredity is in reality religiously obeyed. "The secondary
growths in carcinoma are identical with the primary, for it is the
epithelial element which is infected, and it is this element which
determines in the normal process of development the general anatomy
of the parts around, be they glandular or otherwise. So a columnar
celled carcinoma of the rectum produces in its metastatic growths
intestinal crypts in the liver ; a thyroid cancer produces in its secondary
tumours thyroid tissue in the bones ; an osteoid sarcoma shows in its

574 C. S. SHERRINGTON AND C. A. BALLANCE.

secondary manifestations osteoid tissue ; and it might even be con-
jectured that if the epithelium over the papilla of a hair received the
carcinomatous infection hair-like structures would be found in the
primary and secondary tumours ^" In the production of scar-tissue it
seems to us of transcendent significance that such tissue is characterised
by the possession of cells of which each tends to secrete a coUaginous
capsule for itself, so that around the cells a more or less solid and
fibrillated intercellular matrix comes to be characteristic. Cells with
a similar tendency characterise broadly the connective tissues wherever
found. It is in accordance to laws of natural descent for the cells of
connective tissue, when thrown into renewed and extraordinary genetic
activity in what is termed plastic inflammation, to produce a progeny
of cells possessed of the same tendencies as themselves. And among
all these tendencies which one is more unfailingly repeated in them
than to mould a semi-solid fibrillated collaginous capsule, in short, to
build up fibrous tissue ? But the cells of the blood nowhere show
signs of any such propensity. The colorless corpuscle of the blood is
conspicuously endowed with a character apparently opposed to, even
incompatible with, the formation of a semi-solid circum-cellular test —
the whole story of its normal life so far as we know that, is associated
to one continuous flux of form.

The term "inflammation" is at present employed to signify a
number of phenomena of which some are not only widely dissimilar
one from another, but are even not necessarily associated. John
Hunter recognized the importance of distinguishing two classes of
injuries to tissue, in consequence of the radical differences between the
resulting processes of metabolism set up by them in the tissue and
comprehended within the one term inflammation. He says^, "The
injuries done to sound parts I shall divide into two sorts, according
to the effect of the accident. The injuries of the first division in
which the parts do not communicate externally seldom inflame; while
those of the second which have an external communication commonly
both inflame and suppurate." Modern surgery^ has shown how right
Hunter was. Would it not be well to designate by separate titles the
parts of the inflammatory process due to the plasma-cell of the tissue,
and to the migrated colorless corpuscle of the blood respectively ? By

1 See a discussion of this question, Path. Soc. Trans. Vol. xxxviii. pp. 423 and 424,
1887. Ballance and Sliattock, " Cultivation experiments with Cancer."
- Quoted from Paget's Surgical Pathology, Ed. 4, p. 131.
3 Ihid. p. 130.

ON FORMATION OF SCAR-TISSUE.

575

such a terminology the destructive and suppurative processes of inflam-
mation would be sundered from the constructive and reproductive. ITiis
would obviously be of advantage, if, as would appear likely, pathology
is to teach that pus is an adjunct of the inflammatory process only when
the irritation produced within the tissue is aggravated by the associated
presence of a sufficient dose of bacterial virus.

REFERENCES TO PLATES.
Plate XXXI.

Fig. 1. Contents of experimental chamber that had remained 72 hours
in the peritoneal cavity of the rabbit. Five large amoeboid plasma-cells, with
altered red corpuscles and apparently dead leucocytes. Outlined with camera
lucida. Apochromatic oil immersion and ocular No. 4. Zeiss. Prepared
over osmic vapour.

Fig. 2. Contents of a chamber for 18 hours in the peritoneal cavity
(rabbit) ; near the centre of the chamber. Fibrin filaments, leucocytes, red
corj^tuscles, and an ill-defined granular mass forming a nodal point in the
fibrinous network — the bej]finnin£]|; of a ''cell-islet." Outlined under camera.
Similar method of pre])aration, and similar magnification to preceding.

Fig. 3. Fragment of inflammatory membrane formed within a chamber
placed for three days in the subcutaneous tissue (guinea-pig). Islets and
groups of islets scattered through the membrane. Zeiss, Obj. A, Oc. 2.
Osmic acid solution, and Ehrlich's logwood.

Fig. 4. Contents of same chamber as in Fig 1. Close to the opening of
the chamber. Five plasma-cells, one of them continuing a leucocyte within a
large vacuole. Magnification and method of preparation as in Fig. 1.

Fig. 5. Contents of same chamber. Two plasma-cells and two red
corpuscles ; the plasma-cells are indistinguishably united with fine filaments
of fibrin in their surrounding, some of which are given in the figure. Osmic
acid vapour. Zeiss, apochr. system, oc. No. 2.

Plate XXXII.

Fig. 6. Giant cells from chamber 72 hours in the peritoneal cavity
(rabbit). Zeiss apochr. system, ocul. 5. Osmic acid vapour.

Fig. 7. Plasma-cells from same preparation which furnished Fig, 6.

Fig. 8. "Cell islet" from inflammatory film obtained in a chamber left
eight days in the subcutaneous tissue of the guinea-pig, At the margin it
is united to outlying plasma-cells. Zeiss oil, oc. 4. Osmic acid vapour.

576

G. S. SHERRINGTON AND G. A. BALLANGE.

Fig. 9. YoTing cicatricial tissue of anastomosing branched cells, some of
which are represented under the higher magnification in Fig. 17. From a
thrombosed artery (syphilis) near the centre of the thrombus. Zeiss A,
oc. 3. Logwood. Preparation kindly shown us by Dr Seymour Sharkey.

Fig. 10. "Cell islet" from inflammatory membrane obtained from chamber
five days in the peritoneal cavity of the rabbit. Osmic acid solution. Zeiss
oil imm. and oc. 2.

Fig. 11. Mass of blood-cells (1 clot) surrounded by fibroblastic cells, and
invaded by them at four places. Inflammatory membrane from chamber
eight days in subcutaneous tissue. Magnification as in preceding, and pre-
pared in similar manner.

Fig. 12. Fusiform plasma-cell (fibroblast) surrounded by a fibrillated
material which forms a thread-like band of connective tissue. Zeiss oil and
oc. 4. Osmic vapour. From chamber 10 days in subcutaneous tissue.

Fig. 13. Similar but larger and thicker fibrous band from same prepara
tion. Similar preparation and magnification.

Plate XXXIII.

Fig. 14. From chamber five days in subcutaneous tissue. Plasma-cells
adhering to a cotton-fibre. Osmic vapour and carmine. Zeiss apochr. oil
and 00. 4.

Fig. 15. From chamber eight days in subcutaneous tissue. Plasma-cells
adhering to a hair, which had accidentally been allowed to get into the wound.
Zeiss obj. D, oc. 2. Osmic acid solution and haematoxylin.

Fig. 16. Inflammatory membrane from chamber eight days in the ab-
dominal cavity ; taken from a tenuous portion of the membrane. Four fibro-
blasts, in a film which is composed of an extremely irregularly arranged
network of filaments resembling fine fibrin threads. The processes from the
cell-body are continuous aj)parently with the fibrils of the matrix. Osmic acid
vapour and haematoxylin. Zeiss apochr. oil imm. and oc. 4. Outlined with
camera lucida.

Fig. 17. Stellate fibroblasts and two leucocytes from same preparation
as Fig. 9, more highly magnified. Zeiss apochr. oil and oc. 4. Outlined
with camera lucida.

Fig. 18, The modified Ziegler chamber; the sketch shows the actual
size employed.

Fig. 19. Portion of the chamber seen edgewise, showing the opening
between the cover-glasses. Enlarged 12 times.

CAMBRIDGE : PRINTED BY C. J. CLAY, M.A. AND SONS AT THE UNIVERSITY PRESS.

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